Cell cycle control system
This presentation is the property of its rightful owner.
Sponsored Links
1 / 5

Cell Cycle Control System PowerPoint PPT Presentation


  • 90 Views
  • Uploaded on
  • Presentation posted in: General

Cell Cycle Control System . Checkpoints stop the cycle until go-ahead signal is received. There are 3 checkpoints (G 1 , G 2 , & M) that must be passed before Mitosis is completed. . Molecules associated with the cell-cycle clock.

Download Presentation

Cell Cycle Control System

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Cell cycle control system

Cell Cycle Control System

  • Checkpoints stop the cycle until go-ahead signal is received.

    • There are 3 checkpoints (G1, G2, & M) that must be passed before Mitosis is completed.


Molecules associated with the cell cycle clock

Molecules associated with the cell-cycle clock

  • Cdks - cyclin-dependent kinase (remember that a kinase is an enzyme that activate or inactivate by phosphorylating)

    • cyclin is always present in the cell and is activated when phosphorylated

    • synthesized during the S-phase

  • MPF - M-phase promoting factor

    • partner molecule to Cdk

    • peaks during M phase and initiates Mitosis

    • aids in the disassembly of the nuclear lamina

    • switched off during Anaphase


Molecules associated with the cell cycle clock1

Molecules associated with the cell-cycle clock

  • Growth factor

    • secreted by near-by cells

    • called a mitogen

    • many allow the cell to proceed past the G1 checkpoint

      • if the go-ahead signal is not reached it switches to the G0 phase

        • most adult cells are at this position


External controls

External controls

  • density dependent inhibition

    • cells stop dividing when overcrowded

  • anchorage dependence

    • to divide cells must be anchored


Cancer

Cancer

  • Cancer cells lack the inhibition pathways

    • are immortal or stop at odd places in the cycle

      • HeLa cell line has been dividing since 1951

      • usually 20-50 replications before cell death

    • normal cells are transformed to cancer cells through a transformation process

    • if the cells stay in the same location they are said to be benign

    • if the tumor invades an organ and impair its function, it is said to be malignant

    • when the cancer cells travel to different locations they are metastatic (process is metastasis)


  • Login